1. Field of Invention
This invention relates to the field of energy, specifically to a device that can produce mechanical, pneumatic and electrical energy from river and tidal hydropower sources with maximum efficiency, minimum cost and without producing any greenhouse gases (GHG) emissions.
2. Prior Art
Today, our energy economy seems to be humming along like a perpetual motion machine. Billions of people enjoy an unprecedented standard of living and nations are floating in rivers of wealth, in large part because, around the world, the energy industry has built an enormous network of oil wells, supertankers, pipelines, coal mines, power plants, transmission lines, cars, trucks, trains and ships—a gigantic, marvelously intricate system that almost magically converts oil and its hydrocarbons cousins, natural gas and coal, into the heat, power and mobility that animate modern civilization. For one hundred years this manmade wonder has performed nearly flawlessly until global oil consumption rose to equal or exceed global oil production and oil prices tripled.
The search for new sources of energy has become the most important challenge for the new century. Fully 25% of the world's proven oil reserves sits under Saudi Arabia. Add its four neighboring kingdoms and that number soars to 66%. The absolute cost of carbon-based fuels, particularly petroleum, has increased dramatically over the last decade along with the political and military consequences caused by the world's increasing reliance on it. And now there is a direct connection between petroleum emissions and the increasing problems of global warming, urban pollution and serious health issues for children as well as the elderly.
The world needs to spend one trillion dollars a year in alternative fuels, starting 20 years before the peak in conventional oil production, in order to mitigate fuel shortages, a United States Energy Department study concludes. Production peaks in Texas, the United Kingdom, and Norway were examined as part of two studies for the department that advised on “crash course” efforts to cope with an eventual shortage of gasoline and other liquid fuels. The study didn't predict when world production will peak, though the lead author said within the next five to ten years. Using the lower 48 states of the United States as a model, the study based calculations on a 2% annual decline in world production once the peak is reached, leading to a large global shortage 20 years later. Field declines may well be quicker, he said. To lessen the impact, it concluded, we have to start a long time before the peak or we'll have severe liquid fuels shortages worldwide. Conventional oil production peaked in Texas in 1972, North America in 1985, the United Kingdom in 1999, and Norway in 2001, and all of those peaks were sharp and sudden. To offset losses when world output peaks, “unconventional oil” will need to be rapidly developed, including heavy oil, oil sands, coal liquefaction, gas-to-liquids, enhanced oil recovery and renewables.
Energy production has now been conclusively linked to global warming. Its emissions emit CO2 and particulate that reduces the ozone layer and adds micro-particles to the atmosphere. If our rate of fossil fuel burning continues to grow we could eventually transform Earth into a different planet. A 420,000 year record of carbon dioxide and temperature developed from the study of a 3.6 kilometer ice core recovered from Antarctica demonstrates that the Earth's climate system overreacts to even small nudges. The levels of carbon dioxide and temperature oscillate in a cycle every 100,000 years in step with minute changes in the shape of Earth's orbit around the Sun. These orbital changes that paced the ice ages were incredibly small. They had little effect on the total amount of sunlight reaching the Earth in a single year, only its distribution over seasons and latitudes. Nevertheless, these minute redistributions led to swings in temperature of about 5 degrees C and variations in sea level of more than 100 meters. Greenhouse gases on the other hand control the brightness of the sun—adding a trillion tons of carbon dioxide to the atmosphere thus far in the industrial era which dwarfs the redistributions in sunlight that once switched the planet back and forth between glacial and interglacial. We must now realize that humans control the global climate, for better or worse.
Earth is now passing upward through the highest temperatures of the past 12,000 years and we will soon be only a half a degree from the highest points that have been reached only a few times in the past two million years. If we continue business as usual it has been estimated temperatures will rise between two to three degrees this century, making the Earth as warm as it was about three million years ago when the seas were between 15 to 35 meters higher than they were today.
Harnessing and consuming energy requires some type of energy investment or net energy typically given as per unit of energy invested (EROI). In the 1930's, US oil was easy to recover, in many cases it was almost at the surface and had an EROI of 100:1. Since then oil has gotten deeper, harder to find, more viscous, higher sulfur content, etc, and now has a typical EROI of about 10:1. The total refined EROI of today's oil is somewhere between 5-10:1. In comparison, wind has an EROI of 7:1, solar is 5:1 and ethanol is 1.2:1.
Today, the world uses about 13 terawatts of power, approximately 80 percent of it from carbon dioxide emitting fossil fuels. If we want to keep Earth's average temperature low enough to prevent eventual large sea level rises and also accommodated 3 percent annual economic growth we will need between 10 and 30 terawatts of new carbon free power by 2050. The only solution is to develop an energy that does not produce heat, carbon dioxide, carbon particulate, SO2, and waste products or need an extensive global supply and refining system. Also we do not want an energy producing technology that fills up the countryside with machinery eyesores and noise. Oil certainly does not meet these new requirements, nor does ethanol, biomass or even wind or conventional hydropower. Only solar and tidal and river power meet these high energy standards.
Such a transition of substance will have profound implications for the economy, the environment, and U.S. foreign policy. Thomas Friedman, New York Times columnist and author of “The World is Flat, A Brief History of the Twenty-First Century” has published an article in Foreign Policy magazine, stating that the price of oil and the pace of freedom always move in opposite directions. Many of the Third World countries suffer from polluted cities affecting their tourism, high petroleum import costs and growing power grid failures weakening their economies and their fragile currencies.
Besides the ecological consequences, the rise in oil prices represents a big redistribution of income from those who buy it to those who produce it. This year, oil exporters could haul in $700 billion from selling oil to foreigners. The IMF estimates that oil exporters current account surplus could reach $400 billion, more than four times as much as in 2002. The top net oil exporters are: Saudi Arabia, Russia, Norway, Iran, UAE, Nigeria, Kuwait, Venezuela, Algeria and Libya. This will eventually produce a global political, economic and military power shift from users to producers.
The second most important challenge for the new century is clean water. And energy is the major component of making clean water. The CIA, PricewaterhouseCoopers and, most recently, Britain's Ministry of Defense have all raised the specter of future water wars. With water availability shrinking across the Middle East, Asia and sub-Saharan Africa, so the argument runs, violent conflict between states is increasingly likely.
We may be heading for an era of hydrological warfare in which rivers, lakes and aquifers become national security assets to be fought over, or controlled through proxy armies and client states. By 2025, more than two billion people are expected to live in countries that find it difficult or impossible to mobilize the water resources needed to meet the needs of agriculture, industry and households. Population growth, urbanization and the rapid development of manufacturing industries are relentlessly increasing demand for finite water resources.
In parts of India, groundwater levels are falling so rapidly that from 10 percent to 20 percent of agricultural production is under threat. In the Middle East, the world's most severely water-stressed region, more than 90 percent of usable water crosses international borders. From the Aral Sea in Central Asia to Lake Chad in sub-Saharan Africa, lakes are shrinking at an unprecedented rate. In effect, a large section of humanity is now living in regions where the limits of sustainable water use have been breached—and where water-based ecological systems are collapsing.
Hydropower
Every hour, more energy from sunlight strikes the Earth than is consumed on the planet in a year. But the planet's expansive surface area spreads the energy out into very low energy density levels. Only approximately 1-2 watts/square meter of solar power is available on average. The enormous amount of solar energy absorbed by the entire Earth's surface area transfers via heat and evaporation to the planet's atmosphere which is an enormous heat engine condensing the energy many times over into several types of hydropower where it is many times energy denser and can be harnessed more efficiently.
River Power
The Hydrologic Cycle is the water cycle that is cycling water through the Earth system and it is a cycle of energy as well. Solar energy strikes the earth causing evaporation, the phase change of liquid into a vapor. Evaporation is an important means of transferring energy between the surface and the air above.
Of the renewable energy sources that generate electricity, hydropower is the most often used. It accounted for 7% of US generation and 45% of renewable generation in 2003. Currently mechanical energy is derived by directing, harnessing or channeling moving water. The amount of available energy in moving water is determined by its flow or fill. Swiftly moving water in a big river carries a great deal of energy in its flow. So too water descending from a very high point. In either case the water flows through a pipe or penstock then pushes against and turns blades in a turbine to spin a generator to produce electricity.
Although hydropower is a clean and unlimited source of energy, it often comes with a high price. It is currently dominated by huge expensive dams which displace people, flood vast areas and wipe out fish populations that need open rivers to spawn. Holding back further use of hydropower per has been the lack of an efficient, inexpensive and environmentally friendly device to extract energy from water. Recent studies have shown hydropower to have other major drawbacks. Reservoirs behind the world's large dams now cover almost 600,000 km3, an area nearly twice the size of Italy. Fluctuating water levels of many tropical reservoirs create excellent breeding grounds for malaria and other disease carrying life. Most dams also present insurmountable obstacles to the movement of aquatic species. And large reservoirs have been recently found to be significant sources of greenhouse gases due to the aging of river water. Possibly the major problem with dams is the long term threat to the viability of their reservoirs caused by excessive silting. These high sediment loads also effect the operation of the plant by throttling the feeder tunnels, eroding guide vanes and runner blades. Deposition in reservoirs has effects far downstream as it cuts global sediment flow in rivers by more than 25% and reduces the amount of silt, organic matter and nutrients available to alluvial planes and costal wetlands downstream. As a result some coastlines are eroding at rapid rates.
When considering hydropower one must take into account that rivers have many essential functions. Most major cities of the world are built beside rivers. Commercial river craft need to use rivers for commerce. People use rivers for boating, swimming and fishing. Rivers lend important atheistic value to the area around them. Nature uses rivers to provide a home for plants and animals as well as carry important sediments downstream. Dams interrupt the ecology of the natural river system as well as degrade water quality. Their turbines cause high fish mortality. And dams affect the environment by converting large tracts of land normally used as towns, scenic locations, archeological resources, fish and wildlife habitat, farmland, grazing and other uses into vast reservoirs.
Tidal Power
Production of electricity by harnessing the power of tidal currents is being examined with renewed interest by many industrialized nations. Tidal power systems are being considered for India, Canada, China, Mexico, UK, US and Russia. It has been estimated there is up to 3,000 GW of energy in total global tidal waters. Tidal power has become economically feasible as a result of the continuous rise in the price of fossil fuels. A number of nations already possess working tidal driven electric generating facilities. And tidal power is highly predictable unlike wind and solar.
The generation of electricity from tides is very similar to hydroelectric generation, except that water is able to flow in both directions and this must be taken into account in the development of the generators. The simplest generating system for tidal plants, known as an ebb generating system, involves a dam, known as a barrage constructed across an estuary. Sluice gates on the barrage allow the tidal basin to fill on the incoming high tides and to exit through the turbine system on the outgoing tide. Alternatively, flood-generating systems, which generate power from the incoming tide are possible, but are less favored than ebb generating systems. Power is produced for 6 to 12 hours of every 24 hours.
A (barrage) tidal power plant is similar in principle to hydropower generation facilities. A barrage (dam) with a powerhouse and turbines is constructed across an estuary or bay to form a basin of sufficient size to allow production of electricity over a reasonable period. For the simplest design, the basin is allowed to fill during flood tide through floodgates and powerhouse, with turbines spinning freely and power is produced on ebb tide.
Tidal fences are composed of individual, vertical axis turbines which are mounted within the fence structure, known as a caisson, and they can be thought of as giant turn styles which completely block a channel, forcing all of the water through them. Unlike barrage tidal power stations, tidal fences can also be used in unconfined basins, such as in the channel between the mainland and a nearby off shore island, or between two islands. As a result, tidal fences have much less impact on the environment, as they do not require flooding of the basin and are significantly cheaper to install. Tidal fences also have the advantage of being able to generate electricity once the initial modules are installed, rather than after complete installation as in the case of barrage technologies. Tidal fences are not free of environmental and social concerns, as a caisson structure is still required, which can disrupt the movement of large marine animals.
Tidal turbines have only become reality in the last five years. Resembling a wind turbine, tidal turbines offer significant advantages over barrage and fence systems, including reduced environmental effects. Tidal turbines utilize tidal currents that are moving with velocities of between 4 to 6 knots. Offshore tidal power generation (“tidal lagoons”) is a new approach to tidal power conversion that resolves the environmental and economic problems of the familiar “tidal barrage” technology. Tidal lagoons use a rubble mound impoundment structure and low-head hydroelectric generating equipment situated up to a mile or more offshore in a high tidal range area.
Problems with river and tidal power.
(a) Most devices require a dam, tidal barrage, embankments, caissons or sluices to be built;
(b) Some devices cannot be removable without damage to site;
(c) Many devices create an impediment to aquaculture;
(d) Most devices create greenhouse gas emissions caused by aerobic growth in backup reservoir;
(e) Some devices reduce downstream sediment layering;
(f) Most devices require significant elevation change;
(g) Some devices reduce aeration of water;
(h) Due to their complexity most devices are limited to where they can be sited;
(i) Many devices are not swimmer and boat safe;
(j) Most devices are not safe for fish and river life;
(k) Some devices emit noise;
(l) Many devices have high initial build costs;
(m) Many devices are limited to few river sites in terms of depth, width, speed of water, bottom shape;
(n) Some devices require costly high load capacity roads to be built to site;
(o) Many devices have complicated electrical systems requiring expensive and vulnerable seals;
(p) Most devices cannot be fabricated of recycled materials which decreases their total lifecycle energy costs;
(q) Most devices have an observable outline making them eyesores;
(r) Most devices cannot meet the global strategy required to deal with the successful commercialization of a low-density global energy source. This requires large numbers of devices operating all over the world and includes an ease of transportability across national border;
(s) Many devices change the turbidity of the water;
(t) Some devices alter the salinity of the water;
(u) Most devices create pollutant accumulation;
(v) Some devices have high capital cost;
(w) Many devices have high visibility;
(x) Most devices are an impediment to aquaculture;
(y) Some devices are not safe for fish and tidal area life;
(z) Most devices have high initial build and operating costs;
(aa) Many devices need to be custom configurable for most tidal sites in terms of depth, width, speed of water, bottom shape;
(bb) Most devices are not transportable to site;
(cc) Many devices are difficult to remove without damage to site;
(dd) Many devices do not produce enough energy returned to replace the total energy invested.
(ee) Some devices require extensive anchoring systems which are expensive, time consuming to install and affect marine life.